Brief review of echo and methods in evaluation of valvular heart disease

1. An initiative in the evaluation of
Valvular Heart Disease

2.  Echocardiography remains the most frequently used and usually the
initial imaging test to evaluate all cardiovascular diseases related to a
structural, functional, or hemodynamic abnormality of the heart or
great vessels.
 Uses the ultrasound beams reflected by cardiovascular structures to
produce characteristic lines or shapes caused by normal or abnormal
cardiac anatomy.
 Doppler and colorflow imaging provide reliable assessment of cardiac
hemodynamics and blood flow.

5.  Single dimension
 Graphically represents the motion of cardiac structures.
 Used primarily to measure cardiac chamber size.
 Timing of cardiac events.
 Display subtle abnormalities of cardiac motion.
 For determination of LV mass.
 May overestimate the dimensions if the direction of ultrasound
beam is oblique to that structure.

8.  Volumetric flow
 Spatial pattern of flow
 LV outflow
 RV outflow
 LV inflow
 RV inflow
 Left atrial filling (pulmonary vein flow)
 Right atrial filling (SVC,IVC)
 Descending aorta

9.  Overall pattern of intracardiac flow is better demonstrated.
 Angle dependent.
 Physiologic valvular regurgitation.

10.  Agitated saline
 Specific contrast agents
 For detection of intra cardiac shunts
 For delineation of cardiac borders
 For detection of PFO

12. In evaluation of valvular heart disease

13.  During the past 20 years, echocardiography has gradually replaced
cardiac catheterization for most hemodynamic assessments in most
clinical practices.
 Less than 5% pts undergo hemodynamic cardiac catheterization
before AVR for AS.
 Less than 50% pts undergoing pericardiectomy.
 Doppler hemodynamic assessment is sometimes more reliable,
accurate than invasive hemodynamic assessment, the best example
being Transmitral pressure gradient(PCWP used as LA pressure).

14.  Peak(Maximal) instantaneous gradient is measured(Peak to
peak in invasive).
 Mean gradient – average of pressure gradients during the entire
flow period.
 Bernoulli principle.
 Simplified Bernoulli equation.

15. P = 4V² or (2V) ²
P =pressure difference
V = maximal velocity recorded across orifice by
CW doppler.

16.  The simplified bernoulli equation ignores the proximal flow
velocity (v1) and estimates gradient based on the distal,or jet
velocity (v2),this is an acceptable simplification if v2 is
significantly greater than v1.
 In case of proximal velocity (v1) is relatively high, this
simplification may be inappropriate.
 If the gradient is low,the difference between v1 and v2 may be
relatively small and a more appropriate version of bernoulli
equation would be.
P = 4 (Vd² - Vp²)

17.  Flow velocities recorded with doppler echocardiography are
used to determine various intracardiac pressures.
1.Pulmonary artery pressures
 Tricuspid regurgitation jet velocity gives the systolic pressure
difference between RV and RA.
TRJV =  (RVSP - RAP)
RVSP = TRJV +RAP
RVSP = PASP in absence of any stenosis.

18.  Pulmonary regurgitation velocity represents the diastolic pressure
difference between the pulmonary artery and PV.
PAEDP = RVEDP + 4(PREDV)²
PAEDP = RAP + 4(PREDV)²
PA Mean Pressure = 4(PR peak velocity)² .

19. PRJV
PREDV

20.  AR velocity reflects the diastolic pressure difference between the
aorta and the left ventricle.
LVEDP = DBP – (AREDV)²  4
DBP = Diastolic Blood Pressure
EDV =End Diastolic Velocity.

21. According to the hydraulic orifice formula, flow (rate) across a
fixed orifice is equal to the product of the cross sectional area
(CSA) of the orifice and flow velocity:
Flow rate : CSA  Flow velocity.
In hemodynamic calculations of flow, SV and orifice area by
doppler echocardiography.
TVI – flow velocity varies during ejection in a pulsatile
system,individual velocities of the doppler spectrum need to be
summed (i.e. integrated) to measure the total volume of flow
during a given ejection period.sum of velocities is called time
velocity integral.
SV = CSA  TVI

22.  Mostly LVOT is used to determine the stroke volume.
 CSA of the orifices in the heart is usually assumed to be a circle, and
is determined by measuring the orfice diameter (D)
CSA = (D/2)²  
CSA = D²  0.785
SV = D²  0.785  TVI
Cardiac output = SV  HR
Cardiac index = CO /BSA

23.  Based on conservation of mass.
 A1  TVI1 =A2  TVI 2

24.  Originally developed for evaluating patients with mitral
stenosis.
 Time required for the peak pressure gradient to be reduced by
one half.
 Time required for the peak velocity to decrease to a value
equal to peak velocity divided by 2.
 Time required for the initial velocity to decrease to a value of
peak velocity divided by 1.4.
 Peak velocity multiplied by 0.7
 PHT increases with increase in stenosis.

25.  Volumetric method:
 RV = Aortic systolic flow – Mitral diastolic flow.
 Regurgitant fraction (%) = Regurgitant volume / aortic outflow
volume *100%.
 ROA = flow rate /Velocity

26.  Novel application of continuity principle.
 As blood converges toward an orifice,doppler flow imaging
reveals concentric shells or hemispheres which represent
isovelocity surfaces.
 As the blood accelerates toward the orifice velocity alaising
occurs,distinct red blue interface occurs at the boundary of
shells.
 Velocity is equal to nyquist limit.
 Surface area =2r²
 Flow rate = 6.28  r²  aliasing velocity
 Flow rate =ERO velocity jet

27.  Index of LV contractility
 Rate of LV pressure increase during early systole = dp/dt
 Early mitral regurgitant velocity represents dp/dt as LA
Pressure varies little during isovolumic contraction.
 Measuring the slope of the mitral regurgitation velocity.
 Time interval between 1m/sec and 3m/sec
 dp/dt = 32/time interval
 Good correlation with cath data..
 Normal dp/dt >1200mmhg /sec

28.  Ratio of pressure to flow.
 SVR = MR velocity /LVOT TVI
 SVR = Mean aortic pressure – RA Pressure /CO (cath)
 SVR > 0.27 has 70% sensitivity and 77% specificity for SVR
>14 WU.
 PVR = TR velocity/RVOT TVI* 10+0.16

29.  Workload on right ventricle
 Derived by RHC – strong predictor of survival in patients with
pulmonary hypertension.
 How much aggregate pulmonary artery will dilate with each
RV contraction.
 PVCAP = SV/Pulse pressure of pulmonary artery
 PVCAP = LVOT area* LVOT TVI / 4 (TR velocity² –PR
velocity ²)